On October 16, 1991 something rather sordid happened at Ormond College, at the University of Melbourne, Australia. It was the night of the annual valedictory dinner and dance, and the Master of the college, slightly the worse for drink, came on to one female student in his study and felt the breast of another on the dance floor. Or, depending on your point of view, he didn't. The one thing we can all be certain of here is that one side or the other is lying - to the world, if not to themselves.

Ten months later, when the feminist writer Helen Garner read that the 54-year-old Master had been charged with indecent assault, her sympathies were engaged. But not by the young student's alleged ordeals, but by the plight of a man whose career was on the line. So upset was she, indeed, that she did something which she would later have cause to regret - she sat down and dashed off a letter to him.

"It is heartbreaking," she wrote, "for a feminist of nearly 50 like me, to see our ideals of so many years distorted into this ghastly punitiveness. I expect I will never know what `really happened', but I certainly know that if there was an incident, as alleged, this has been the most appallingly destructive, priggish and pitiless way of dealing with it."

The Ormond case has uncanny echoes in what's become known as the "Reading case", which has been played out over recent weeks here in Britain. A university professor, aged 53, is accused of making improper advances to two young female students after a college party. He is questioned by police and he winds up in the crown court. His wife and grown-up children rally round him. It ends up all coming down to the students' words against his ...

Last month, this professor, John Cottingham, who is head of the philosophy department at Reading University, was cleared of indecent assault. The jury and the media seem to have found him entirely plausible.

Just imagine though, if when the story first broke, a prominent British feminist commentator, who knew none of the details of the case, had reached for the Basildon Bond to dash off a letter to the professor to say, in effect, "Maybe you did it, maybe not, but, hey, this is surely more than you deserve" ... Now, wouldn't that have caused a stir?

"I look back on that letter with amazement," says Garner, unable, even now, fully to explain what compelled her. "It was just a spontaneous gesture of distress. I didn't stop to think, `Wait a minute, maybe this bloke is a sleazebag from way back and at last they've managed to trip him up' That didn't cross my mind. Oh, now, of course, it would. My days of writing spontaneous letters are over."

Unfortunately, the students' supporters at Ormond saw the letter. Garner found herself both drawn into and excluded from the public debate which grew up around the scandal. She turned her experiences of this into a book, The First Stone, which caused a furore when it appeared two years ago, when the Ormond issue was red hot in Australia. By then, the controversy was fuelled by personal animus; there were howls of outrage at the idea that Garner had ratted on the sisterhood.

Now the paperback is on sale here in Britain, where it has the same relevance, the same resonances, but where the name of Ormond means nothing, and where, as the author herself cheerfully puts it, "people don't know me from a bar of soap''. Whether it will, therefore, provoke a more measured response, remains to be seen.

At the same time as Garner began her exploration of the Ormond debacle, other women closed ranks around the two students. She, who had written so impetuously to the man she calls Colin Shepherd in the book (all names book have been changed to protect the innocent - whoever they may be), was assumed to have permanently taken his side. Meeting this small, slight, eminently reasonable and pretty woman, a 55-year-old mother with gamin haircut and easy, friendly manner, it is impossible to see her as the arch traitor, but this was how she was perceived.

"It looked like I was taking a position from the start," she says. "The man, when he received the letter, because he was going down the googla, photocopied it and passed it around. That was wrong of him, but he was in desperate straits. I put the letter fairly far up-front in the book because it shows that I did have a kind-of slant on it, but I still don't know why the story gave me such a stab. I think it might have been a very far-back connection with when I got the sack, when I was a teacher in 1972. It was terrible, and it completely changed the course of my life."

Easier, though, for her at just 30, than for Dr Shepherd today? "Exactly. The age thing, and also the fact that he's a man, and that mud sticks. He'll never get another job."

Shepherd has been less fortunate than Cottingham. He was at first found guilty, and although he was cleared on appeal, it was an iffy sort of vindication, just a matter of reasonable doubt in a case that came down to the balance of oath against oath. The media had by then already done for him. His position at Ormond was untenable; wretched, he resigned.

"There are many occasions," Garner allows, as she muses in the implications of all this, "in which women are really at a sort of systemic disadvantage, when you get really heavy-duty sexual harassment, and I'm very much in favour of provisions being made within institutions, and of laws to have teeth to deal with that. I just kept wanting to stress the room to move that there is before you get to the police."

In the face of the refusal of the two central female players to meet with her and talk, she has done her best to put herself in their place. `'I spent a lot of time trying to see the thing from their point of view, trying to understand how, for them, this incident, which to us looks so minor, fitted into the whole picture of harassment of women, or just hassling of women inside the college by various people, and there being no recourse for them."

"Some of the feminist critics of the book said I had derailed the debate," Garner relates a shade wearily, "that I'd started talking about harassment in a way that they didn't want it talked about." Which is to misunderstand, surely, the nature of debate.

The readers, meanwhile, wrote in great numbers. Hate mail poured in, and with it letters of support. People told how they had coped in similar situations. Young women protested that they weren't all so flaky; they could give as good as they got. "Several women who'd been raped wrote and said `I agree with you.' I think it insults those women who've been through such intense and appaling experiences, to hear that someone calls it `violence' if a man puts his hand on your breast while dancing.''

When she went ahead and published, Garner must have known that she'd be damned. Even so, she was not prepared for the sheer nastiness of certain responses. "Sometimes I would have these kind of panic attacks caused by the hostility that some people showed towards me. I guess I knew there was going to be trouble, but the vitriolic nature of it gave me a bit of a shock.

"The worst stuff came from feminists directly connected with the women's chief supporter," she said. "I'm not saying she was manipulating them, but there was a culture and a particular strand of sensibility around those women's position on things, that saw everything I said as a kind of outrage."

Her own 28-year-old daughter and her peers took a broader view. "They tended to agree with me that to go to the police was an overreaction, or would bring about devastation that was inappropriate to the offence." More depressingly, men who had read only about the book would congratulate the author for, as they imagined, putting the boot in for them.

At the eleventh hour, the two students went to court to try to prevent publication. They failed. On the advice of her lawyers, meanwhile, Garner had shown her manuscript to Dr Shepherd. Strikingly, he did nothing to oppose publication, although he described himself as being "shattered" by it.

Shepherd's critics had no victory before the law. Yet he was brought down, he was publicly wrecked, and this might be seen as a victory of a sorts. I don't know.

What stays with me is Garner's account of her interview with Mrs Shepherd, who stood by her husband throughout it all. Not with the gritted teeth of the stoic wife of a philandering politician, but with absolute love and trust. A sweet woman, she went through a pile of tissues in the course of two hours, she wept and wept. It was terrible, she said, to feel so powerless. And, "I do begrudge that he won't have a pleasant end to his life."

A man, his wife, his children are all in pieces. This punishment is out of all proportion to the crime: discuss